scusa, ma nel tuo caso basta scrivere, con il pacchetto colortbl:
`
\begin{table}[!pt]
\centering%
\def\arraystretch{1.2}
\begin{tabular}{ccccl}
\hline
\rowcolor{blue}
\multicolumn{2}{>{\columncolor{blue}}c}{A} &B &\multicolumn{2}{>{\columncolor{blue}}c}{C} \\
\hline
\rowcolor{green}
600.00& 1093.20 &802.00&
\multicolumn{2}{>{\columncolor{green}}c}{$(1.62\pm 0.15)\times\power{10}{-5}$} \\
\rowcolor{gray}
1093.20 &1991.83 &1461.25 &
\multicolumn{2}{>{\columncolor{gray}}c}{$(3.18\pm 0.37)\times\power{10}{-6}$}\\
\hline
\end{tabular}
\caption{PIPPO}%
\label{tab:pippo}%
\end{table}
`
oppure con il pacchetto xcolor, con opzione table:
`\rowcolors{1}{gray}{green}
\begin{table}[!pt]
\centering%
\def\arraystretch{1.2}
\begin{tabular}{ccccl}
\hline
\rowcolor{blue}
\multicolumn{2}{>{\columncolor{blue}}c}{A} &B &\multicolumn{2}{>{\columncolor{blue}}c}{C} \\
\hline
600.00& 1093.20 &802.00&\multicolumn{2}{>{\columncolor{green}}c}{$(1.62\pm 0.15)\times\power{10}{-5}$} \\
1093.20 &1991.83 &1461.25 &\multicolumn{2}{>{\columncolor{gray}}c}{$(3.18\pm 0.37)\times\power{10}{-6}$}\\
\hline
\end{tabular}
\caption{PIPPO}%
\label{tab:pippo}%
\end{table} `
ciao
Andrea